A number of pyridazinone (sometimes called pyridazone) compounds are known.
U.S. Pat. No. 3,377,154 describes ester substituted derivatives of 5-amino-4-halo-2-phenyl-3(2H)-pyridazinones as herbicides.
German Patent No. 1,670,295 teaches the use of 4,4,5,5-tetra-halo-3(2H)-pyridazinones as flame retardants.
U.S. Pat. No. 4,011,321 describes 6-(3-substituted amino-2-hydroxypropoxyphenyl)-4,5-dihydro-3(2H)-pyridazinones as .beta.-adrenergic blocking agents.
U.S. Pat. No. 4,397,854 pertains to selected 6-phenyl-4,5-dihydro-3(2H)-pyridazinones which are useful in pharmaceutical compositions as cardiotonic agents. While the pyridazinones of this patent may be selectively substituted on the 6-phenyl group, the instant compounds having a hindered phenolic moiety at the 6-position of the 3(2H)-pyridazinone are not disclosed or suggested. This patent is totally silent as to whether the cardiotonic agents set forth therein, each having a pyridazinone moiety in the molecule, have any stabilization properties as well.